a=2.
print(type(a)),print(a)
a=.5
print(type(a)),print(a)
a=10.0**2
print(type(a)),print(a)
a=10.0**-307
print(type(a)),print(a)
a=10.0**306
print(type(a)),print(a) #超出浮点范围
a=10.0**-322
print(type(a)),print(a) #超出浮点范围